Error message for invalid preload argument incorrectly states that only arity 1 functions are supported

[stiang]

Elixir version

1.15.5

Database and Version

PostgreSQL 16.1

Ecto Versions

3.12.5

Database Adapter and Versions (postgrex, myxql, etc)

postgrex 0.19.3

Current behavior

I’m trying to use arity 2 preload functions, and in the process I have inadvertently supplied invalid values for the preload keyword several times, which threw the following error:

** (ArgumentError) invalid preload for key `:enabled_partner_features`: &ApiServer.V1.Partners.enabled_partner_features/2. Preloads can be a query, a function (arity 1), or a dynamic that evaluates to a single binding.

This comes from assert_query_or_fun!/2 in lib/ecto/query/builder/preload.ex.

Expected behavior

Arity 2 functions are supported since 3.12 (I believe), so I think the error message just needs to be updated to reflect that fact.